The B_s --> mu+mu- and B_d --> mu+mu- Decays: Standard Model and Beyond

I review the status of the rare decays B_s --> mu+mu- and B_d --> mu+mu-. The latest Standard Model predictions for the corresponding branching ratios are discussed. An overview of additional observables that are accessible in the B_s --> mu+mu- decay is given. The new physics implications of the recent measurement of the B_s --> mu+mu- branching ratio are discussed both model independently and in the context of the Minimal Supersymmetric Standard Model.